The specific aims of the proposed research are the following: (a) Development and application of new psychometric methods (b) Generation of nontechnical papers on research methodology (c) Creation of tutorials to improve methodology in drug abuse research (d) Consultation to NIDA and its grantees on methodology. The research program is directed towards the development of new multivariate psychometric and statistical techniques that hold special promise for improving the quality of research on the psychological, social, behavioral, epidemiological, and health-related antecedents and consequences of drug and alcohol abuse. Special attention is devoted to methods of structural modeling that can test theories of drug abuse on data obtained under natural conditions. Major efforts are directed to the development of methods that yield appropriate statistical inferences when applied to the type of data usually observed in substance abuse research, that is, non-normally distributed variables exhibiting substantial multivariate skew and/or kurtosis. While no data will be gathered under this grant, the newly developed techniques will be extensively evaluated for their practical relevance to drug abuse research by addressing important substantive issues in drug abuse on high-quality data obtained in association with the UCLA/NIDA program, via collaboration with nationally active substance abuse researchers working on their own projects, as well as by cooperation with NIDA and other health-related agencies. Methods that are developed under this grant and elsewhere will also be widely disseminated via goals (b) and (c) above.